The physical connector through which an electrical device communicates data with another device is referred to as an “interface port”, or simply “port”. Two compatible devices can communicate by connecting together their respective ports, either directly or through an electrical cable.
In order for two devices to communicate data, they typically must employ a common data interface protocol, also referred to as a communications protocol. Examples of industry-standard data interface protocols are USB (Universal Serial Bus), MS (Memory Stick), SD (Secure Digital), MMC (Multi-Media Card), and CF (Compact Flash). These protocols are commonly used by computers, digital cameras, digital music players, mobile telephones and video games.
When two devices are communicating, if one device controls the communication, the controlling device is referred to as a “host”, and the other device is referred to as a “peripheral device”. Peripheral devices, especially portable peripheral devices, often receive their operating power from a host device through the interface port rather than having their own independent source of operating power such as a battery.
A “data interface circuit” within a device is responsible for implementing a specific data interface protocol for transferring data between some circuitry within the device and a port, where the port is intended to be connected to another device capable of communicating in accordance with that protocol. In a peripheral device, a data interface circuit also is referred to as a “host interface circuit”. Electrical devices commonly include a plurality of data interface circuits that implement different data interface protocols to enable communication with other devices that employ any of these protocols.
Most of the industry-standard data interface protocols require a physical port that is unique to that protocol, so that the port required by one data interface protocol usually is incompatible with the port required by any other protocol. To achieve physical compactness, portable devices, such as portable non-volatile memory devices, typically include only one or two physical ports, and hence are compatible with only one or two corresponding data interface protocols. Therefore, if a manufacturer of such portable devices wants to offer products compatible with different industry-standard data interface protocols, the manufacturer typically offers a different model of portable device for each type of data interface protocol.